Introversion and High Sensitivity

Hello, and welcome back to the Sensitive Life Well Lived!

In my last posting, I briefly discussed how introversion and high sensitivity can often overlap, but they are not the same. And, although there is overlap, not all HSPs are introverts and not all introverts are HSPs. So, what exactly do HSPs and introverts have in common? And how are they different?

Definitions

To start, let’s define what exactly I mean when I say “introvert.” Introversion, like sensitivity, and like a lot of traits in nature, exists on a spectrum. There are very few pure introverts, just as there are very few pure extroverts, and most people end up somewhere in the middle. However, according to the Myers Briggs Company, at least 50% of the global population is on the more introverted side of the curve, earning them a label of “introvert.”

Most people have an idea of what an introvert is: shy, quiet, awkward, the kind of person who prefers books to other people. And that’s not necessarily a wrong definition, but it is not entirely true either. Susan Cain discusses this is in her excellent book, Quiet (highly recommended for introverts and those who want to understand them). There is no one-size-fits-all definition for introvert vs. extrovert because individual people are complex, and every introvert experiences life differently. But she does suggest some traits that her research has led her to believe are defining qualities of the introvert. “Feel ‘just right’ with less stimulation,” “work more slowly and deliberately,” “like to focus on one task at a time,” “dislike conflict,” “listen more than they talk,” “think before they speak,” “often feel as though they can express themselves better in writing,” “have a horror of small talk, but enjoy deep discussion,” (page 11). She also includes definitions of what introverts are not: “hermits or misanthropes,” “not necessarily shy,” (page 11-12).

            In contrast, high sensitivity has a set definition, coined by Elaine Aron in 1996. She believes that the highly sensitive person is one who has a “ sensitive nervous system, is aware of subtleties in his/her surroundings, and is more easily overwhelmed when in a highly stimulating environment.”

What do High Sensitivity and Introversion Have in Common?

            Introverts and HSPs both prefer a world that is quieter, slower and more reflective. They are capable of great friendships, but prioritize quality over quantity. Our modern pace of life, what Susan Cain calls “the extrovert ideal,” is often just too much for both introverts and HSPs. This overstimulation can drive introverts and HSPs away from activities typical for an extroverted culture, and into pursuits that are more solitary and cerebral, such as books, music and nature. This can often make them seem like the “weird ones.”  As a personal example, in nursing school, as both an introvert and HSP, I sometimes declined classmates’ relatively frequent invitations for drinks on the weekends, preferring to unwind with a book or a walk. I am still friendly with most of my former classmates, but left nursing school with only a few relationships I would define as real friends.  

“Introverted” and “highly sensitive” are also both life-long identities; introverted or sensitive children grow up to be introverted or sensitive adults, as described in Chapter 4 of Quiet.

 Both are also at least partly genetic, although high sensitivity is likely more heritable than introversion

What are the Differences?

As I said above, introversion and high sensitivity are both at least partly inherited. However, introversion is also likely a product of the environment you are raised in. Cultures that are more individual-focused, such as the US and Western Europe, claim a larger proportion of extroverts than cultures that are more collective-focused, such as Asia, as discovered by Susan Cain in Chapter 8 of Quiet. This means that, even if you had inherited the tendency to be extroverted, but were raised in an “introverted” environment, you will likely fall more towards the introverted side of the spectrum and vice versa.  High sensitivity on the other hand, appears to be less influenced by your environment. In contrast, 15-20% of the population is an HSP; a figure that holds true across cultures, races, genders, and even species, meaning it is much more likely to be due to genetics.

Introverts prefer to turn inward, where the world is calm. Highly sensitive people also often find the outside world overwhelming, however HSPs can just as easily be overwhelmed by their own internal stimuli. An important acronym to remember in the care and feeding of your HSP is HALT: Are they Hungry, Angry, Lonely or Tired? All of these are significant internal stimuli for all people, leading to increases in instances such as work errors or drug and alcohol abuse. Like all other stimuli, however, HSPs feel them particularly strongly. HSPs are also prone to “flooding,” or becoming so overwhelmed by their own emotions that they are incapable of making rational, logical decisions.

This difference can be explained by brain anatomy. As I stated in my previous post, the brain and nervous system work by sending electrical signals down neurons. Certain electrical signals code for molecules known as neurotransmitters, each of which has a particular message to convey, and gets sent from one neuron to another. Each neuron has slots to receive certain kinds of neurotransmitters, and then sends out an electrical signal accordingly. Two of these neurotransmitters are dopamine and acetylcholine. Dopamine’s main job is in the “reward” pathway. Get a 100% on your exam, or excellent feedback on your presentation at work? That feeling of accomplishment is brought to you by dopamine. But dopamine is not just for good rewards. Dopamine also regulates the euphoria of drugs, gambling and other addictive behaviors. Acetylcholine is much quieter. It regulates the body’s ability to “rest and digest,” such as slower heart and breathing rates, and feelings of relaxation. Less pleasure, more contentment.

Here’s where things get interesting. Research is still ongoing, but suggests that those who identify as extroverts have more dopamine in their brains. They are driven to seek “rewards.” Bigger parties, louder music, riskier bets, etc., feel good to an extrovert because it stimulates their dominant reward pathway (Quiet, Chapter 7). Research suggests that by comparison, those who identify as introverts have more acetylcholine in their brains. They are driven to seek quiet and relaxation because it stimulates their dominant “rest” pathway.

Regardless of if you are an introvert or an extrovert, the brain and body strive for balance. Too much dopamine can lead to destructive or risky behaviors (Quiet, Chapter 7) Too much acetylcholine, especially for an extrovert, causes boredom, and thrill seeking, which can also be dangerous. The mix should be optimal, although “optimal” look different to extroverts than introverts.

Highly sensitive brains simply have more neuron connections. So, they are able to be more attuned to whatever neurotransmitter is in their brain at the moment than neurotypicals, regardless of if the neurotypicals are extroverted or introverted. HSPs will feel flooded by dopamine at much lower levels even than introverts because they are just more aware of what little there is. There is too much dopamine, so they will seek solitude to decrease their levels. They will also feel overwhelmed by acetylcholine at much lower levels even than extroverts, and will seek stimuli to balance it out. Fortunately for the HSP, it usually does not take much.

Conclusion

            All people, regardless of their place on the introversion/extroversion spectrum, or the sensitivity spectrum, are different, and will see the world through a different set of eyes. That’s one of the things that makes life so beautiful. But, new research is starting to unravel what makes us tick, in the broad sense, and I am excited to continually discover more, and to have you, dear reader, along with me for the journey.